1. Technical Field
The disclosure relates to a paper feeding device configured to feed sheets.
2. Related Art
A printer such as an inkjet printer or a stencil printer includes a paper feeding device configured to send out sheets from a paper feed tray and convey the sheets to a printing unit. In such a paper feeding device, a paper feeding roller sends out each sheet one by one on the paper feed tray to an intermediate conveying roller, and the intermediate conveying roller sends out the sheet to a registration roller. A leading edge of the sent-out sheet abuts on the registration roller and temporarily stops.
The intermediate roller continues to send out the sheet toward the registration roller after the leading edge of the sheet stops. Accordingly, the sheet forms sag between the registration roller and the intermediate conveying roller until the registration roller starts to rotate. This sag corrects skewing of the sheet and the sheet whose skewing is corrected is sent out to the printing unit with the rotation start of the registration roller.
A motor driving the paper feeding roller is stopped by deceleration control after the leading edge of the sheet reaches the intermediate conveying roller. The motor is connected to the paper feeding roller via a one-way clutch, and the paper feeding roller is rotated by following the sheet after the motor stops. The following rotation of the paper feeding roller continues until a trailing edge of the sheet passes the paper feeding roller.
Stopping the motor for the paper feeding roller by the deceleration control requires a certain amount of time. Accordingly, when the trailing edge of the sheet passes the paper feeding roller before the motor stops, the paper feeding roller ends the following rotation, but continues to rotate for a while by the drive of the motor and sends out the subsequent sheet in the paper feed tray slightly. Due to this, the subsequent sheet is sent out from the paper feed tray sometimes at incorrect timing.
Japanese Unexamined Patent Application Publication 2009-40568 propose a technique of sending out a sheet to a printing unit at correct timing. In this technique, when a sensor arranged between a paper feeding roller and a registration roller detects a leading edge of the sheet, the speed of a conveying roller conveying the sheet is reduced from a first speed to a second speed. In this speed control, the second speed is set higher as the timing at which the sensor detects the leading edge of the sheet becomes later.